The implantation of occlusive systems for fully or partially occluding a natural conduit of a patient is known for different indications. For example, the treatment of urinary incontinence can involve implantation of an artificial sphincter in a patient.
Such a sphincter typically comprises an occlusive element placed around the urethra (in men or women) or sometimes the bladder neck (in women) or the prostate (in men) with the aim of exerting direct or indirect compression on the urethra to prevent urinary leaks, an activation device of said occlusive element to vary compression exerted on the urethra or the bladder neck, as well as a control unit of the activation device.
Such an artificial sphincter is described in particular in [1].
Different technologies of artificial sphincters have been proposed, based especially on different types of occlusive elements and associated activation mode.
According to an embodiment, the occlusive element is an inflatable cuff comprising a variable volume of fluid.
The activation device is a hydraulic device, comprising a reservoir of said fluid and an electromechanical actuator for adding or withdrawing said fluid to compress or decompress the cuff.
Such an artificial sphincter is described for example in [2].
Another example of an artificial sphincter is described in [3].
There is also an electromechanical sphincter, wherein the occlusive element is a band surrounding the urethra or the bladder neck and connected to a cable which exerts more or less strong tension on the band [4].
Due to the compression exerted by the occlusive element, the region located under said element is poorly vascularised, such that the nutrition of the tissues is locally reduced.
This then becomes localised thinning, or atrophy, of compressed tissues.
This atrophy is reversible if it is detected sufficiently early; so, if the compression of the cuff is relaxed for a while, the tissues regenerate and thicken again.
Atrophy of the conduit is the cause of a decrease in efficacy of the occlusive system over time since, as the diameter of the conduit becomes smaller, the occlusive element can no longer achieve the preferred occlusion.
To remedy this, it is proposed either to replace the implanted occlusive element by another one of lesser diameter, or to increase the compression pressure to compensate for the decrease in diameter of the conduit [4], [5], [6].
But, both solutions require a fresh surgical procedure with the attendant risks (infection, etc.) and/or cause also a higher risk of lesion or erosion of the conduit.
A lesion and/or erosion of the tissues—that is, localised rupture of the wall of the conduit—can occur when a considerable degree of atrophy has been attained.
Lesions of non-treated tissues or erosion of tissues can augment the risk of infection, to the extent where bacteria present in the urethra can colonise the affected tissues.
To treat a lesion and/or erosion, it is necessary to perform a fresh surgical procedure to remove the implanted system.
A lesion or erosion of tissues therefore constitutes a serious case of complication of the implantation of the occlusive system.
Erosion is not an isolated phenomenon since meta-analysis on 2606 artificial urinary sphincters [5] showed that 12% of patients implanted with an artificial urinary sphincter suffer from erosion.
It would therefore be desirable to be able to detect atrophy as early as possible to be able to prevent a lesion or erosion of the conduit.
Direct measurement of atrophy, consisting of measuring the diameter of the part of the conduit surrounded by the occlusive element, is not feasible as it would be highly complex to execute in an implanted system.
Currently, none of the occlusive systems proposed on the market can detect any atrophy.
This is therefore only when the patient notices a malfunction of the occlusive system—especially with the appearance of leaks—that the practitioner can consider the conduit has atrophied.
An aim of the present invention is therefore to design an implantable occlusive system for reliably detecting any atrophy and as soon as possible consequently alerting the practitioner or the patient.